As the number of devices connected to data networks increase and higher data rates are required, there is a growing need for new transmission technologies enabling higher transmission rates over existing copper cabling infrastructures. A current effort to that end is the development of a standard for 10 Gbit/sec Ethernet transmission over twisted-pair cabling (10GBASE-T). The emerging 10GBASE-T physical layer (PHY) specification is intended to enable 10 Gbit/sec connections over twisted-pair cabling at distances of up to 182 feet for existing cabling, and at distances of up to 330 feet for new cabling, for example. To achieve full-duplex transmission at 10 Gbit/sec over four-pair cabling, elaborate digital signal processing techniques are needed to remove or reduce the effects of severe frequency-dependent signal attenuation, signal reflections, near-end and far-end crosstalk between the four pairs, and external signals coupled into the four pairs either from adjacent transmission links or other external noise sources. Moreover, new cabling specifications are developed to diminish susceptibility to external electro-magnetic interferences.
A pair of 10GBASE-T PHY transceivers on each side of a link must initially be trained during a start-up procedure to adapt transmitter and receiver settings to the specific characteristics of the link. The start-up procedure may include establishing initial synchronization, setting transmit power levels, adjusting echo and near-end crosstalk cancellers, adjusting equalizers, selecting and exchanging precoding coefficients, etc. Elaborate start-up procedures are known in the art, for example those used in voiceband modems. Some start-up procedures are aimed at achieving relatively short start-up times. For lower-rate PHY transceivers prior to 10GBASE-T, real-time execution of start-up specific functions meeting the requirements of time-critical handshake procedures usually did not pose severe problems. For 10GBASE-T, where start-up time may not be a critical issue, minimizing the means required for accomplishing start-up specific functions may be more important. Hence there is a need for a start-up procedure that permits performing such functions by shared hardware, firmware, or software at far less than real-time speed in exchange for a longer start-up time. Then only functions needed for sustained continuous data transmission, such as long digital filters or decoders for error correction decoding, must be realized by highly efficient hardware that can perform these functions in real time.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.